Phosphors comprising silicates, phosphates (for example, apatite) and aluminates as host materials, with transition metals or rare earth metals added as activating materials to the host materials, are widely known. As blue LEDs, in particular, have become practical in recent years, the development of white light sources utilizing such blue LEDs in combination with such phosphor materials is being energetically pursued.
Especially luminescent materials based on the so-called “SiAlON”-system have found the focus of attention in the field due to their good optical features.
However, there is still the continuing need for luminescent materials which are usable within a wide range of applications and especially allow the fabrication of phosphor warm white pcLEDs with optimized luminous efficiency and color rendering.
Especially in the field of red emitting phosphors, several materials have been the subject of investigation.
E.g. in the EP1696016A1 the material CaAlSiN3:Eu is described as a new red phosphor powder. The material shows a highly saturated red emission, however this implies a low lumen equivalent of the emission spectrum and therefore a low lumen output of light sources which use this phosphor. For general lighting applications higher lumen equivalents are favourable due to the higher efficiencies they enable.